This relates generally to electronic devices and, more particularly, to electronic devices having pressure sensors for gathering information about the electronic device and the environment.
Electronic devices often include sensors and other circuitry for detecting movement of the electronic device and for characterizing its surroundings. For example, inertial sensors such as an accelerometer or gyroscope are sometimes used to detect a rapid change in acceleration or orientation. Global Positioning System receiver circuitry and/or IEEE 802.11 (WiFi®) transceiver circuitry are sometimes used to determine where the electronic device is located. Infrared proximity sensors are used to detect when an electronic device is being held against a user's ear during a telephone call so that display and touch sensor circuitry can be temporarily disable during the call.
However, the decisions that an electronic device makes based on these types of sensors and circuitry may not always be reliable. Measuring vertical displacement with an accelerometer requires double integration of accelerometer data, and the noise associated with the accelerometer data may be too high to do this reliably. Global Positioning System receiver circuitry typically cannot be used inside of a building because the building blocks satellite signals. WiFi®-assisted positioning can be inaccurate due to multiple reflections of the radio signals. Infrared light from an infrared proximity sensor may be absorbed by dark hair, making it difficult to detect the user's head near the electronic device.
It would therefore be desirable to provide improved circuitry and methods for detecting movement and determining vertical displacement of an electronic device.